In the prior patent applications there has been described a spectrophotometric method and apparatus directed to non-invasive, continuous, atraumatic, in vivo, in situ monitoring of metabolism in a body organ. In the described applications, measuring and reference wavelengths within the near-infrared region, i.e., 700-1300 nm, are utilized for non-invasive, continuous, atraumatic, in situ, in vivo monitoring of oxidative metabolism by monitoring oxygen sufficiency in an internal organ, e.g., the brain or heart, of a human or animal body. Advantage is taken of the critical characteristic of cellular enzyme cytochrome, a, a.sub.3 (also known as cytochrome c oxidase and identified by EC 1.9.3.1) within the optical path and within the radiated portion of the selected organ for absorbing the selected measuring wavelength and for light of this measuring wavelength, as well as at least one reference wavelength within the same defined infrared region and at a low, non-hazardous level of intensity to be detectable at the end of a relatively long transillumination or reflectance path, e.g., of several centimeters length, which may include substantial content of bone as well as soft tissue and skin. Variations in metabolic and circulatory parameters during measuring are recognized and the selection of wavelengths, circuitry and method also provide techniques for compensating for changes in blood volume in the organ being monitored, for continuous monitoring of hemoglobin oxygenation and blood volume, for intermittent monitoring of blood flow rate, for skin blood flow effects and variations in the light source, i.e., laser diode, output.
In view of the fact that the prior art has been discussed extensively in the prior patent applications, such discussion will not be repeated here. The discussion to be found in the prior patent applications should thus be treated as incorporated herein by reference.
In the context of the mentioned prior patent applications and prior art, the present invention is primarily concerned with the light source and light detecting structure at the place of attachment to the body and with the means for mounting the light source-light detecting structure on the body. Thus, the present invention is primarily intended to provide an improvement over the light source-light detecting structure shown in copending application Ser. No. 188,578 as well as over all known prior art deemed relevant to the invention. A useful background of the prior art may be had by making reference to the discussion of the prior art in the mentioned prior patent applications and to the light source and light detecting structures described in U.S. Pat. Nos. 3,527,932; 3,674,008; 3,638,640; 3,704,706; and 4,077,399.
Taking all of the foregoing into account, further development and experimentation with the spectrophotometric apparatus and method for measuring local metabolism described in the mentioned patent applications has revealed the need for an improved means for securing and shielding the light sources as well as the light detectors when attached to the body and particularly in reference to improving the light source-detector mounting arrangement described in copending application Ser. No. 188,578. Also, a need has arisen for further simplification of the light source-light detecting structure which is attached to the body and to the associated mounting structure such that it can be made economically in a disposable form and where necessary for a single end use application such as in a surgical operation, emergency accident situations, and the like.
The achievement of these various needed improvements thus becomes the general object of the invention and other objects will be revealed as the description proceeds.